MORPHOLOGY:
The average body mass for adult males range between 700 to 1100 grams, and for females the range is between 500 to 750 grams. The common squirrel monkey has a short digestive tract indicative of insectivory. The cheek teeth have large cusps assists the common squirrel monkey in eating insects (Fleagle, 1988). Males have longer canines than the females (Fleagle, 1988). The tail of the common squirrel monkey is prehensile in infants but the adults lose this ability. The body has a long trunk and hindlimbs and also possesses a long tail (Fleagle, 1988).

RANGE:
The common squirrel monkey is found in the countries of Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, and Venezuela; a small population has been introduced to Southern Florida. This species prefers rainforests, and can adapt to different kinds of rainforests. The common squirrel monkey prefers to live in the middle canopy, but will occasionally come to the ground or go up into the high canopy.

ECOLOGY:
The common squirrel monkey is considered both frugivorous and insectivorous, preferring berry-like fruit on terminal branches. They also forage for molluscs, and small vertebrates, such as tree frogs. They obtain a majority of water from the foods eaten, and will also obtain water from holes in trees and puddles on the ground. When fruit is scarce, the common squirrel monkey will forage on nectar (Terborgh, 1983). In Peru this species will follow groups of Cebus monkeys to find fruit trees (Podolsky, 1990). This species is arboreal and diurnal.

LOCOMOTION:
The common squirrel monkey travels through the forest quadrupedally on the branches and leaps when it moves in the lower stories of the forest (Fleagle, 1988). This species uses quadrupedal positions when it feeds (Fleagle, 1988).

SOCIAL BEHAVIOR:
In the common squirrel monkey groups females form alliances with other females, and there exists a dominance hierarchy amongst the females of the group (Kinzey, 1997). Social interactions are centered around a group of dominant females, much like some prosimian species (Fleagle, 1988). The males of this species disperse and the females are philopatric (Kinzey, 1997). The males form all male groups (Kinzey, 1997). A dominant male usually monopolizes most of the copulations during the breeding season (Kinzey, 1997).This species sometimes forms mixed-species associations with Cebus olivaceus and Cebus apella, and this could occur to increase feeding efficiency and for predator defense (Mendes Pontes, 1997). The young are cared for by other females as well as the mother, but not by any males (Fleagle, 1988).

VOCAL COMMUNICATION:chuck calls: For female squirrel monkeys these calls communicate spatial and foraging context within the group (Boinski and Mitchell, 1997).

OLFACTORY COMMUNICATION:urine-wash: This is when a common squirrel monkey will spread urine on the bottoms of the hands and feet. Then when the individuals walks, the urine is spread upon the substrate. It is used to spread olfactory cues.

VISUAL COMMUNICATION:penile display: This when a male common squirrel monkey places his hand on the back of another male, then turns the leg and thigh out so that the male can see his erect penis. This display is used to maintain dominance. The dominant male sometimes thrusts his penis at the other male, and even will urinate on the subordinate male.

TACTILE COMMUNICATION:

REPRODUCTION:
The common squirrel monkey gives birth to a single offspring. Males gain body mass during the breeding season, up to 222 grams (Kinzey, 1997).